"This is not an isolated case," urged Renan Ferraciolli, Procon's top lawyer. "There's no need to appeal as they do to children without the maturity or the rationality to enter the market as consumers."

In the past year, this girl probably saw around 1,000 ads for fast food.Bans on ads are a frequent occurrence in Europe, but in the U.S. they gain less traction. Last year, a San Franciso judge dismissed a class-action lawsuit seeking to ban Happy Meal toys in California. But the lawsuit shows that concern is growing, and McDonald's is increasingly the target.

The ban on free toys in unhealthy meals had been introduced one year previously in another California jurisdiction, Santa Clara County.

County Supervisor Ken Yeager explained the reason for the ordinance, claiming that it "prevents restaurants from preying on children's love of toys" to sell fast food, and that it "breaks the link between unhealthy food and prizes."

Chile:

McDonald's began offering apples in its Happy Meals in 2011. AP Photo/Keith Srakocic Chile issued a similar law in June 2012, requiring fast food restaurants, cereal brands, and popsicle makers to eliminate the practice of including free toys, crayons, and stickers in their packages.

In a sign that such laws are serious for fast food chains, KFC reacted by changing their marketing outlook. "What we have done," said marketing director Virginia Ng, "is stopped marketing to kids in anticipation of the global movement of marketing to children being unethical...We offer meals for families, but the toys and the rest of it, no."

Is McDonald's slipping?

Though it began offering healthier options, like apple slices in Happy Meals, in 2011, McDonald's has stood its ground in the face of Happy Meal naysayers. "We are very proud of our Happy Meals and will vigorously defend our brand, our reputation and our food," said spokeswoman Danya Proud.

Having topped growth records in recent years, this year's slowdown shows that times are changing for the restaurant chain. Matthew DiFrisco of Lazard Capital, a market research firm, rates McDonald's as 'Neutral'— he believes its stocks will remain cheaply valued moving forward.